Curtis 3301T - 6 - CANopen COMMUNICATIONS; CANopen Data Format

6 — CANopen COMMUNICATIONS
Curtis Model 3301T Digital Instrumentation – September 2021
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6 — CANopen COMMUNICATIONS
e 3301T complies with the CAN in Automation (CiA) CANopen DS 301 specication. is chapter
describes the 3301T’s CANopen features.
Some familiarity with CANopen is a prerequisite. For CANopen information, see the following pages
on the CiA web site:
• Overview: https://www.can-cia.org/canopen/
• Specications: https://www.can-cia.org/groups/specications/
BYTE AND BIT SEQUENCE ORDER
CANopen message byte sequences are transmitted with the least significant byte first (little-
endian format).
Note: is manual uses the LSB 0 Numbering convention when referring to byte and bit numbers.
For example, the following table shows an SDO that writes the data 04E2h to the object with the
index and sub-index 334C-01h:
0 1 2 3 4 5 6 7
Control Byte Index Sub-index Data
2Bh 4Ch 33h 01h E2h 04h 00h 00h
Strings are read from le to right. e following example shows how the 3301T transmits an SDO
segment for the string “3301T-7”:
0 1 2 3 4 5 6 7
Control Byte Data
00h 33h = “3” 33h = “3” 30h = “0” 31h = “1” 54h = “T” 2Dh = “-” 37h = “7”
Bit sequences are transmitted from most signicant to least signicant bit (big-endian format). e
following example shows how the 3301T transmits the bits for the value 2Bh:
7 6 5 4 3 2 1 0
0 0 1 0 1 0 1 1